KR20070108198A - Intervertebral Prosthetic Disc with Shock Absorption - Google Patents

Abstract

The prosthetic disc for insertion between adjacent vertebrae comprises a core having an upper plate and a lower plate and a curved upper and lower surface disposed between the plates. At least one of the plate and / or core comprises an elastic material to absorb the impact or other force exerted by the vertebrae. Optionally, an elastic support member may be disposed in the elastic material to connect the two portions of the plate or core. Such support members may be springs, cylinders, wires, or other elastic structures. The elastic material is retained in the core or plate (s) via enclosing structures such as membranes. An elastic material disposed on one or more elements of the prosthetic disc provides shock absorbency.

Core, Plate, Exterior, Internal, Disc, Prosthetics

Description

Intervertebral prosthetic disc with shock absorbing property {INTERVERTEBRAL PROSTHETIC DISC WITH SHOCK ABSORPTION}

The present invention relates to medical devices and methods. More specifically, the present invention relates to intervertebral disc prostheses.

Low back pain has a significant impact on the health and production activities of people around the world. According to the American Society of Orthopedic Surgeons, nearly 80% of Americans sometimes experience back pain in their lives. In 2000 alone, nearly 26 million visits were made by physicians in the United States because of spinal problems. At some point in the past, it was estimated that 5% of the US workforce loses its workforce by back pain.

One common cause in low back pain is injury, degeneration and / or dysfunction of one or more intervertebral discs. The intervertebral discs constitute the spine as soft tissue structures located between the 33 respective vertebral bones. In essence, these disks allow the vertebrae to move relative to each other. These vertebrae and discs are central anatomical structures in that they form a central axis that supports the head and torso, allow movement of the spine, and protect the spinal cord passing through the vertebrae near these discs.

Discs are often damaged by wear and tear or serious injuries. For example, the disks may protrude, tear, rupture, degenerate, or the like. Protruding discs may press on the spinal cord or nerves present in the spinal cord, causing "spinal nerve root" pain (pain in one or more limbs caused by impingement of the nerve roots). Regression or damage to the disc may cause a loss of "disk height" which means reducing the original spacing between the two vertebrae. The reduced disk height protrudes the disk, increases the facet load of the vertebrae, and may cause the two vertebrae to rub against each other with increased pressure on some part of the vertebrae and / or nerve roots and / or excessively. Cause pain. In general, chronic and severe damage to the intervertebral discs is a common cause of lumbar-related pain and loss of mobility.

If one or more damaged intervertebral discs cause pain and discomfort in a patient, surgery is often needed. Typically, surgical procedures for intervertebral disc treatment have included disc ablation (partial or complete removal of the disc), in which two vertebrae adjacent to the disc become fused or unfused. Fusion of the two vertebrae is accomplished by inserting a bone graft material between the two vertebrae so that the two vertebrae and the graft material grow together. Often, pins, rods, screws, frames, and the like are inserted between the vertebrae, acting as support structures for retaining the vertebrae and implant material in place, permanently fused together. Fusion often treats spinal pain, but this reduces the patient's ability to move, because the spine cannot bend or twist in the fused area. In addition, fusion increases stress on the spine at adjacent heights, potentially accelerating the degeneration of these discs.

In attempts to treat disc-related pain without fusion, alternative methods have been developed to insert an implantable artificial intervertebral disc (or “disk prosthesis”) that can move between two vertebrae. Various types of intervertebral disc prostheses are currently being developed. For example, the inventors of the present invention have developed the disc prostheses described in US Patent Application Nos. 10 / 855,817 and 10 / 855,253, which are already incorporated herein by reference. Examples of other intervertebral disc prostheses include LINK® SB Charite disc (provided by DePuy Spine, Inc), Mobidisk® (provided by LDR Medical (www.ldrmedical.fr)), Bryan Cervical Disc (provided by Medtronic Sofamor Danek, Inc.), ProDisc ® or ProDisc-C® (Synthes Stratec, Inc.) and PCM disc (provided by Cervitech, Inc.). Existing disc prostheses provide an advantage over conventional therapies, but improvements continue.

One form of intervertebral disc prosthesis includes an upper and lower prosthesi plate or shell that opposes and engages adjacent vertebral bodies and a low friction core between the plates. Include. For example, FIGS. 1 and 2 show the design of one intervertebral disc prosthesis, and are fully described in US Patent Application No. 10 / 855,253 (Representative Listing No. 022031-000310US) and already incorporated herein by reference. have. In some designs, the core has a convexly curved top and bottom surface and the plate has a corresponding concavely curved recess that cooperates with the curved surfaces of the core. This causes the plate to slide over the core to produce the required spine movement. Some form of motion limiting structure is provided to prevent the core from slipping between the plates. Typically, the plates are made of one or more metals and the core is made of a polymeric substance.

Many improvements have already been made in intervertebral disc prostheses. For example, discs with partially or wholly metallic cores to reduce the wear and tear of the cores are described in US Patent Application No. 10/903913 (Representative List No. 022031-001400US), which is herein incorporated by reference. It is already included. Additional improvements continue to be found. For example, currently available intervertebral prostheses do not provide cushioning or shock absorbing ability to absorb the force exerted from the vertebrae to which they are attached.

Therefore, there is a need for improved intervertebral disc prostheses. Ideally, these improved prostheses provide shock absorption of the force exerted by the spine.

In one aspect of the invention, the intervertebral disc prosthesis comprises a core having a curved top and bottom surface and an upper plate and a lower plate disposed around the core. Each plate has, in turn, a curved inner surface that has a shape that can slide over one of the curved surfaces of its core and the outer surface that engages one spine. In addition, at least one of the upper plate and the lower plate includes at least one elastic material disposed between the outer surface and the inner surface. In some embodiments, each top and bottom plate comprises at least one elastic material between its outer and inner surfaces. Any suitable elastic material can be used, for example, but not limited to, polymers, hydrogels, and the like. In various embodiments, the elastic material may be a liquid, semi-solid, gel, solid material or multilayer solid material.

In some embodiments, the elastic material is disposed in one or more layers between the outer and inner surfaces. Such embodiments may optionally include at least one retaining member disposed between the outer and inner surfaces around the elastic material to retain the elastic material between the outer and inner surfaces. For example, the retaining member may comprise a membrane such as, for example, a non-porous membrane, a mesh, or the like. In some embodiments, the membrane comprises a polymer. Optionally, the prosthesis may further comprise at least one elastic support member disposed in the material layer (s) and attached to the outer and inner surfaces of each plate. For example, such resilient support members may comprise a plurality of springs, cylinders, lines, and the like. In one embodiment, each spring is surrounded by a first cylinder extending from the outer surface and a second cylinder extending from the inner surface, one of the first and second cylinders having an outer diameter of a size that fits into the inner diameter of the counterpart cylinder. This allows the small cylinder to move in and out of the large cylinder in response to the movement of the spring. Another embodiment includes a first cylinder extending from an outer surface, a second cylinder extending from an inner surface and at least partially extending into the first cylinder, wherein the locking mechanisms restrict their movement relative to each other, wherein the first and The second cylinders are slidably movable relative to each other.

Various embodiments of intervertebral disc prostheses may have many other design changes to increase or decrease shock absorption. For example, in one embodiment, the endplate may have a thicker or higher endplate to allow more elastic material than in the endplate in other embodiments. The density of the elastic material may be chosen to give different levels of shock absorption. Likewise, the stiffness of an elastic support member such as, for example, a spring or a cylinder, may be chosen to give different levels of shock absorption. Therefore, any of many variables can be adjusted to give the disc prosthesis the desired amount of shock absorption. For example, this variability may be useful in making other disc prostheses for use in cervical vertebra where more rigid prostheses may be desirable.

In some embodiments, the outer surface of the at least one plate comprises a retaining ring, the inner surface of which is fitted within this retaining ring. In such an embodiment, with the outer surface heated and the inner surface positioned in the retaining ring, the outer surface may be allowed to cool and shrink, thus maintaining the inner surface in the retaining ring. The manufacturing method of such a prosthesis is further described below.

In some embodiments, the core consists of a polymer, ceramic, metal or some combination thereof. For example, the metals may include cobalt chromium molybdenum, titanium, stainless steel, and the like. In some embodiments, the elastic material is further disposed between the curved top and bottom surfaces of the core. Optionally, the prosthesis may further include at least one elastic support member disposed within the elastic material and attached to the curved upper and lower surfaces. For example, any suitable elastic support member may be used, such as springs, cylinders, wires, etc., as described above.

Any suitable material, such as, for example, a ceramic material or one or more metals selected from the group consisting of cobalt chromium molybdenum, titanium and stainless steel, may be used to construct the outer and inner surfaces of the plate. In some embodiments, the outer surface of the plate is made of one material, such as a metal, and the inner surface of the plate is made of another material, such as other metals or ceramic materials. In some embodiments, the core and the outer and inner surfaces comprise the same metal. In some embodiments, the prosthesis further includes a restraining structure on at least one of the top plate, the bottom plate, and the core to maintain the core against the curved face of at least one of the plates while the plates slide over the core. . For example, the restraint structure may comprise parallel restraint structures. In a typical embodiment, the movement of the core in the organic structure is free.

Optionally, the outer surfaces of the upper plate and the lower plate may have at least one surface form to facilitate attachment of this outer surface to the vertebrae. For example, the surface form (s) may include a plurality of teeth disposed along an outer surface, a surface coating of plasma spray titanium, a plurality of recesses formed by aluminum oxide blasting, one or more disposed on each outer surface. It may also include a fin.

In another aspect of the invention, the intervertebral disc prosthesis includes a core and an upper plate and a lower plate disposed around the core. The core includes a curved top and bottom surface and at least one elastic material disposed between the curved top and bottom surfaces. Each plate includes an outer surface that engages one spine and a curved inner surface that is shaped to slide over one of the curved surfaces of the core. As mentioned above, the elastic material may comprise any suitable material, for example, but not limited to, polymers or hydrogels. In general, the core and plate may comprise any material or features described above. In some embodiments, one or two plates may comprise an elastic material or other elastic material contained within the core. Any or all of the cores and plates may also comprise membranes connecting the plurality of cores and / or plates separated while surrounding the elastic material and / or the elastic support structures disposed within the elastic material.

In another aspect of the invention, a method of manufacturing an end plate of an intervertebral disc prosthesis includes the steps of forming an outer surface of the end plate so that it can engage the spine, and a curved inner surface of the end plate of the disc prosthetic core. Slidingly forming on the surface, connecting the outer surface and the inner surface with at least one elastic support member disposed between the two, and disposing an elastic material between the outer surface and the inner surface to surround the elastic support member (s). Steps. For example, in one embodiment connecting the outer and inner surfaces with the resilient support member includes attaching a plurality of springs between the two surfaces. Placing the elastic material between the outer surface and the inner surface may include injecting a polymer, a hydrogel, or other suitable elastic material. In some embodiments, the elastic material is injected into a cavity formed between the inner and outer end plates. In other embodiments, the elastic material is injected into the restraint structure disposed between the inner and outer end plates. Alternatively, disposing the material between these faces may include disposing one or more layers of solid material therebetween. Optionally, the method may further comprise coupling at least one restraint structure with the outer and inner surfaces around the elastic material to retain the elastic material between the outer and inner surfaces.

In another aspect of the invention, a method of manufacturing an end plate of an intervertebral disc prosthesis includes the steps of forming an outer surface of the end plate so that it can engage the spine, and a curved inner surface of the end plate of the disc prosthetic core. Coupling the outer surface to the inner surface so as to be slidable on the surface, disposing the elastic material between the outer surface and the inner surface, and confining the elastic material between the outer surface and the inner surface.

In another aspect of the invention, a method of making an end plate of an intervertebral disc prosthesis comprises the steps of forming an outer surface of an end plate that is adapted to engage the vertebra and includes an inner opposing retaining ring, the curved inner surface of the end plate. Forming an slidable surface on the curved surface of the disc prosthetic core, placing the elastic material in the outer surface, placing the inner surface in the retaining ring of the outer surface so as to contain the elastic material between the two surfaces and the inner surface in the retaining ring. Contracting at least a portion of the outer surface to maintain it. In some embodiments, retracting the outer surface includes cooling the outer surface, and the method further includes heating the outer surface before placing the curved inner surface in the retaining ring.

These and other forms and embodiments are described in more detail below with reference to the drawings.

1 is a front sectional view of an intervertebral disc prosthesis in which a prosthetic plate and a core are mounted in a vertical arrangement according to one embodiment of the invention.

2 is a side view of the prosthetic disc in FIG. 1 after the plate moves over the core.

3 is a front sectional view of an intervertebral disc prosthesis having an impact absorbing endplate in accordance with one embodiment of the present invention.

4 is a front sectional view of an intervertebral disc prosthesis having an impact absorbing end plate and a core in accordance with another embodiment of the present invention.

Figure 5 is a cross-sectional view of the end plate of the intervertebral disc prosthesis according to an embodiment of the present invention.

6 is a cross-sectional view of an end plate of an intervertebral disc prosthesis in accordance with another embodiment of the present invention.

Various embodiments of the present invention generally provide for intervertebral disc prostheses having an upper plate and a lower plate disposed around a central core. At least one of the plate and / or the core comprises an elastic material, which allows the plate (s) and / or core to absorb the force exerted by the vertebrae. While various embodiments of such prostheses are shown in the figures and further described below, the general principles of the present invention, i.e., including the material that absorbs forces in the prosthesis, may be applied to any of many other disc prostheses, For example, LINK® SB Charite disc (powered by DePuy Spine, Inc), Mobidisk® (powered by LDR Medical (www.ldrmedical.fr)), Bryan Cervical Disc (powered by Medtronic Sofamor Danek, Inc.), ProDisc® or ProDisc-C® ( Synthes Stratec, Inc.) and PCM disc (provided by Cervitech, Inc.), but are not limited to such.

As described above, FIGS. 1 and 2 show the prosthetic disc 10 already described in U.S. Patent Application No. 10 / 855,253 (Representative List No. 022031-000310US) by the assignee of the present invention and is herein incorporated by reference. Included. The disc 10 for intervertebral insertion between two adjacent vertebrae (not shown) suitably includes an upper plate 12, a lower plate 14 and a core 16 located between the plates. The upper plate 12 includes an outer surface 18 and an inner surface 24 and may be composed of any suitable metal, alloy or combination of metals or alloys, for example cobalt chromium molybdenum, titanium (eg 5 Grade titanium), stainless steel, and the like. In one embodiment, the upper plate 12, typically used for lumbar spine, consists of cobalt chromium molybdenum, and the outer surface 18 is followed by titanium plasma spray followed by aluminum oxide spraying. In another embodiment, the upper plate 12, typically used for cervical vertebrae, consists of titanium, the inner surface 24 is covered with titanium nitride, and the outer surface 18 is aluminum oxide spray treated. Alternative embodiments of the cervical spine do not include coating the inner surface 24. In other embodiments of the cervical and lumbar vertebrae, other suitable metals or metal combinations may be used. In some embodiments, it may be useful to combine the two materials together to form the inner surface 24 and the outer surface 18. For example, the top plate 12 may be made of an MRI-compatible material, such as titanium, but may comprise a harder material, such as cobalt chromium molybdenum, for the inner surface 24. In another embodiment, the top plate 12 may comprise a metal and the inner surface 24 may comprise a ceramic material. All combinations of materials are envisaged within the scope of the present invention. Any suitable technique may be used to join the materials together, for example snap fitting, slip fitting, lamination, interference fitting, adhesive use, welding, and the like. Other combinations of materials and coatings may be employed in various embodiments of the present invention.

In some embodiments, the outer surface 18 is planar shaped. Often, in order to improve the attachment of the prosthesis 10 to the spinal canal, the outer surface 18 will include one or more surface shapes and / or materials. For example, the outer surface 18 may be machined to have a tooth 20 or other surface shape to promote adhesion of the upper plate 12 to the spine. In this embodiment, the teeth 20 extend in a direction orthogonal to each other, but other geometric arrangements are also useful. In addition, the outer surface 18 may be provided with a rough microfinish formed by spraying aluminum oxide fine particles or the like. In some embodiments, the outer surface may be titanium plasma sprayed to further enhance the attachment of the outer surface 18 to the vertebral bone.

The outer surface 18 may have upright vertical fins 22 extending in the front-rear direction. This pin 22 is penetrated by the transverse holes 23. In alternative embodiments, the pins 22 may be rotated spaced apart from the front and rear axes, for example, rotated in a lateral-lateral orientation, a posterolateral-anterolateral orientation. In some embodiments, pin 22 may extend at an angle other than 90 ° from face 18. In addition, in various embodiments, a plurality of pins 22 may be attached to the face 18 and / or the pins 22 may have other suitable configurations. In some embodiments, all of the pins 22, 42 may be omitted, such as the cervical spin disc 10.

A spherically curved concave inner surface 24 is formed with a circular recess 26 mounted at the center (right to left) axis position. At the outer edge of this curved face 24 is provided a circumferential restraint structure in which the upper plate 12 constitutes an integral ring structure 26, including an inwardly directed rib or flange 28. The flange 28 forms a part of the U-shaped member 30 joined to the main part of the plate by the annular web 32. The flange 28 is tapered inwardly and defines upper and lower surfaces 34 and 36, respectively, which are slightly inclined relative to the horizontal line when the upper plate 12 is in the orientation shown in FIG. The overhang 38 of the U-shaped member 30 has a vertical dimension directed inwardly as shown.

The lower plate 14 is similar to the upper plate 12 except that there is no circumferential restraint structure 26. Therefore, the lower plate 14 has an outer surface 40 that is flat, serrated, and treated with a fine finish, such as the outer surface 18 of the upper plate 12. The lower plate 14 is optionally equipped with a pin 42 similar to the pin 22 of the upper plate. The inner surface 44 of the lower plate 14 is concave spherically curved with a radius of curvature that matches the radius of curvature of the inner surface 24 of the upper plate 12. Once again, this side may be provided with titanium nitride or other finish.

At the outer edge of the curved inner surface 44, the lower plate 14 has an inclined ledge shape 46. Optionally, lower plate 14 may include a circumferential restraint structure similar to circumferential restraint structure 26 on upper plate 12.

The core 16 of the disk 10 may be made of any suitable polymer. Optionally, core 16 may be made partially or entirely of one or more metals, alloys or combinations of metals or alloys. For more details on the disk 10 partially or wholly equipped with a metal core, reference may be made to US patent application Ser. No. 10/903913 (List of Representatives No. 022031-001400US), which is already incorporated herein by reference. have. For example, the metals used to form all or part of the core 16 include, but are not limited to, cobalt chromium molybdenum, titanium (eg, grade 5 titanium), stainless steel, and the like. In some embodiments, the core 16 may be made of the same material as the upper plate 12 and the lower plate 14, which helps to prevent oxidation of the metal side of the disk 10. In alternative embodiments, the core 16 may be made of different material (s) than the flat plates 12, 14. In this embodiment, the core 16 has the same convex, upper and lower surfaces 48, 50 that are spherically curved. In some embodiments, the entire core 16 is a metal, while in other embodiments the curved faces 48, 50 may be covered or laminated with metal, or one or more metal faces may be in different ways. 16) may be attached. In some embodiments, the core 16 consists of a polymer or ceramic, to which the metallic curved faces 48, 50 are attached. Optionally, core 16 may be a hollow metal structure. The radii of curvature of these faces coincide with the radii of curvature of the inner surfaces 24, 44 of the upper and lower plates 12, 14. The curved faces are therefore complementary.

The core 16 is symmetrical around a central equator plane 52 that traverses from side to side (in other embodiments, the core 16 may be asymmetrical). Overlying this equator is an annular recess or groove 54 extending around the circumference of the core. The groove 54 is defined between the upper and lower ribs or the lip 56. When the plates 12, 14 and the core 16 are assembled and in the orientation shown in FIG. 1, the flanges 28 lie on the equator plane and are aligned in line with the grooves 54. The outer diameter 58 of the lip 56 is preferably slightly larger than the diameter 60 defined by the inner edge of the flange 28. In some embodiments, the core 16 is movably fit into the top plate 12 by an interference fit. Any suitable technique may be used to form an interference fit with the metal core 16 and the metal plate 12. For example, plate 12 may be heated to expand and core 16 may be inserted into plate 12 in an expanded state. When the flat plate 12 cools and contracts, an interference fit is created. In other embodiments, the upper plate 12 may be formed around the core 16. Optionally, core 16 and top plate 12 may include complementary threads, which allow core 16 to thread into top plate 12 and then move freely.

In an alternative embodiment (not shown), the outer diameter 58 of the lip 56 may be slightly smaller than the diameter 60 defined by the inner edge of the flange 28. In this embodiment, the core 16 and the plates 12 and 14 are not joined by an interference fit but instead by forces applied by the vertebrae themselves, thus resembling ball-and-socket joints. It works.

The central axis of the disk 10 (the axis passing through the center of curvature of the curved surface) is indicated by reference numeral 62. As shown in FIG. 1, the disk 10 may be symmetrical around a central front and rear surface including the axis 62. In some embodiments, the shaft 62 is disposed to the rear, i.e., closer to the rear limit than to the front limit of the disk.

In use, the disk 10 is surgically implanted between adjacent vertebrae in place of the damaged disk. Adjacent vertebrae are forced apart from one another to provide space for insertion. Disc 10 is typically, but not necessarily, advanced toward the disc space from the front or front approach and inserted in the back direction (ie, from front to back). With the pins 22, 42 of the plates 12, 14 embedded in opposing vertebral faces in the slots cut to accommodate them, the disc is inserted into the space between these vertebrae. During and / or after insertion, the spine, articular surface, adjacent ligaments and soft tissues move together to keep the disc in place. The serrated and finely finished surfaces 18, 40 of the plates 12, 14 are positioned against the opposite vertebrae. The teeth 20 and pins 22, 42 provide initial stability and fixation for the disk 10. Over time, as the bone tissue grows over the tooth surface, a solid connection between the plates and the vertebrae is achieved, enhanced by the titanium surface coating. Growth of bone tissue will also occur around the pins 22 and 40 and through the transverse holes 23 therein, which further enhances the connection to be obtained.

In the assembled disk 10, the complementary and interacting spherical faces of the plate and the core are in all directions or degrees of freedom over a fairly wide range of angles, including rotation about the central axis 62. Make it slip against the core or engage the joint. 1 and 4 show that the disk 10 and the core 16 on which the flat plates 12, 14 are mounted are arranged perpendicular to each other on the axis 62. 2 shows a situation where the maximum front bending of the disk 10 has occurred. As can be seen in the enclosed area 69, in this position, the upper rib 56 enters the hollow portion 38 of the U-shaped member 30, and the lower surface of the rib 56 moves and flanges. It comes into contact with the top face 34 of 28, the flange moves into the groove 54, and the bottom face 36 of the flange moves to contact the top face of the ledge 46. The abutment between the various faces prevents further front bending. This design also allows the inner distal end of the flange 28 to abut against the base of the groove 54, thereby limiting further relative movement between the core and the plate. Similar configurations are obtained in the case of maximum back flexion of the plates 12, 14, for example during spinal elongation and / or in the case of maximum lateral flexion.

The flange 28 and groove 54 defined between the ribs 56 prevent the core from being separated from the plates. In other words, the cooperation of the retaining formations allows the core to remain held between the plates at all times while the disk 10 is bending.

In alternative embodiments, the continuous annular flange 28 may be replaced with a retaining formation that constitutes many flange segments that are spaced apart apart. This embodiment may include a single continuous groove 54, as in the illustrated embodiment. Optionally, as many groove-shaped recesses as are spaced apart around the core may be used with each flange segment facing one of these recesses. In other embodiments, continuous flanges or a plurality of flange segments may be replaced with inwardly directed pegs or pins provided in the upper plate 12. This embodiment may include a single continuous groove 54, or a series of recesses spaced apart, with each pin or peg facing one recess.

In another embodiment, the retention formation (s) may be provided in the lower plate 14 instead of the upper plate, ie the plates are reversed. In some embodiments, the upper (or lower) plate is formed of inwardly directed grooves, or groove segments spaced away from the periphery, curved at their inner edges, and the outer edges of the cores facing outwardly, or It is formed of flange segments spaced apart.

Referring to FIG. 3, one embodiment of an intervertebral prosthetic disk 110 similar to that shown in FIGS. 1 and 2 except for the shock absorbing capability is shown (emphasis is shown that the disk 110 of FIG. 3 is not drawn to scale). ). Many features of the disk 110 are similar to those described above in FIGS. 1 and 2 and will not be described again. In the embodiment shown in FIG. 3, the prosthetic disc 110 includes two plates 130, 132, each plate having an outer surface 118, 140 that includes fins 122, 142 while engaging the spine. ) And curved inner surfaces 124, 144 that slide over corresponding curved surfaces of the core 116. Additionally, the "upper" plate 130 (which may actually be the "lower" plate 132 depending on how the disc 110 is disposed between the two vertebrae) is a layer of elastic material 112 A plurality of elastic support members 114 are disposed through the elastic material 112, and a portion of the flat plate 130 including the outer surface 118 is connected to the portion of the flat plate including the inner surface 124. have. Constraining structure 120 surrounds the elastic material to be constrained between portions of outer surface 118 and inner surface 124 of plate 130.

In various embodiments, the top plate 130, the bottom plate 132, the core 116, or any combination thereof includes one or more elastic materials 112 disposed in one layer or includes other configurations. You may. The elastic material 112 may be, for example, a polymer, hydrogel or other similar elastic material. Material 112 may be in liquid, gel or solid form. When in liquid form, the elastic material 112 may often be injected at locations within the one or more plates 130, 132 and / or the core 116. If in solid form, one or more layers of solid elastic material 112 may be disposed within one or more plates 130, 132 and / or core 116. The elastic support structures 114 may be made of any suitable material, such as stainless steel, Nitinol ™, and the like, and may be of any suitable configuration, for example, a spring (see FIG. 3), a wire, a cylinder, a joint, or a band ( band), but is not limited thereto. Any number of support structures 114 may be used. The elastic material 112 and the support structure 114 cause the plate 130 to absorb impacts or other forces exerted on the plate by the spine. Constraining structure 120 is wrapped around elastic material 112, and in various embodiments may be a membrane, mesh, or the like, and may be made of any material capable of retaining the elastic material while also considering shock absorption.

4, an alternative embodiment of intervertebral disc prosthesis 210 includes two plates 230, 232, each plate engaging fins 222, 242 while engaged with the spine. 218, 240 and curved inner surfaces 224, 244 that slide over the curved corresponding surface of the core 216. Additionally, each "top" plate 230, bottom plate 232 and core 216 include a layer of elastic material 212. Plates 230, 232 are disposed throughout the elastic material 212 and each plate 230, 232, 232 includes a portion of each plate 230, 232 that includes outer surfaces 218, 240. And a plurality of elastic support members 214 connected to the portion 232. Constraining structure 220 surrounds each layer of elastic material 212 to hold it in plate 230, 232 or core 216.

In this embodiment, the resilient support member 214 is a cylinder, and in some embodiments each may surround a spring. Core 216 includes two curved faces 236 with elastic material 212 disposed therebetween and held together by restraint structure 220. In alternative embodiments, core 216 may include elastic support structures. In some embodiments, the elastic material 212 may be injected through the restraint structure 220 to the plates 230, 232 and their positions within the core 216.

Referring to FIG. 5, one embodiment of a flat plate 330 of an intervertebral disc includes an outer 316, curved surface with an outer surface 318, a fin 322, and a glass ring 340 facing inward. And an elastic material 312 disposed between the interior 324 having the interior and the exterior 316 and the interior 324 having the curved surface. The plate 330 places the elastic material 312 in the exterior 316, the interior 324 with the curved surface in the retaining ring 340, and the interior 324 in the retaining ring 340. It is configured by shrinking the exterior 316 to retain. For example, because the exterior 316 can be expanded by heating, the interior fits through the retaining ring 340, and then the interior 324 because the exterior 316 is shrunk by cooling. ) Is fixed in the retaining ring 340. Thus, the elastic material 312 is retained between the exterior 316 and the interior 324. Additionally, the interior 324 with the curved surface freely moves up and down within the exterior 316, depending on the elasticity of the elastic material 312, thereby providing shock absorbing capability. At the same time, the retaining ring 340 prevents the interior with the curved surface from being separated from the exterior 316. In an alternative embodiment, the interior 324 with the curved surface may not be heated outside because it may be located within the exterior 316 after being contracted by cooling.

With reference to FIG. 6, an alternative embodiment of the plate 430 of the intervertebral disc includes an outer 416 having an outer surface 418, a fin 422, and an retaining ring 440 facing inward, An elastic material 412 disposed between the interior 424 having a face and the interior 424 having a curved face. In this embodiment, the exterior 416 is coupled with the interior 424 via the plurality of elastic support members 414. Although shown as a spring in FIG. 6, in alternative embodiments, the elastic support member 414 may include a cylinder, a spring surrounded by the cylinder, a Nitinol outer ear, or the like, as described above. In addition to the elastic support member, the flat plate 430 is configured in the same manner as the flat plate 330 in FIG. The density and amount of elastic material 412 used, the number and stiffness of the elastic support members 414 used, and / or the height of the flat plate 430 may vary the performance of the plate 430 to select the desired amount of shock absorption. All may be changed in the example.

While the invention has been described completely and precisely as described above, any number of modifications, additions, and the like may be made in various embodiments without departing from the scope of the invention. Therefore, nothing set forth above should be construed as limiting the scope of the invention described in the claims.

Claims (56)

A core having a curved upper and lower surface, An upper plate and a lower plate disposed around the core, Each plate is External surfaces that engage the spine, A curved inner surface having a shape that can slide over one of the curved surfaces of the core, At least one of the upper and lower plates further comprises at least one elastic material disposed between the outer and inner surfaces. The method of claim 1, Wherein each of said upper and lower plates comprises at least one elastic material disposed between its outer and inner surfaces. The method of claim 1, The at least one elastic material comprises an intervertebral disc prosthesis. The method of claim 1, The at least one elastic material intervertebral disc prosthesis, characterized in that it comprises a hydrogel. The method of claim 1, The at least one elastic material is intervertebral disc prosthesis, characterized in that it is disposed in one or more layers between the outer surface and the inner surface. The method of claim 5, And at least one retaining member disposed between the outer and inner surfaces about the elastic material to retain the elastic material between the outer and inner surfaces. The method of claim 6, And the retaining member comprises a membrane. The method of claim 7, wherein The membrane is intervertebral disc prosthesis, characterized in that selected from the group consisting of a porous membrane, a nonporous membrane and a mesh. The method of claim 7, wherein Intervertebral disc prosthesis, wherein the membrane comprises a polymer. The method of claim 5, And at least one elastic support member disposed in the material layer (s) and attached to the outer and inner surfaces of each plate. The method of claim 10, The at least one elastic support member includes a plurality of springs intervertebral disc prosthesis. The method of claim 11, Each of the springs is surrounded by a first cylinder extending from the outer surface and a second cylinder extending from the inner surface, such that the smaller cylinder moves in and out of the larger cylinder as the spring moves. The intervertebral disc prosthesis, wherein one of the second cylinders has an outer diameter sized to fit the inner diameter of the counterpart cylinder. The method of claim 1, A first cylinder extending from said outer surface, A second cylinder extending from said inner surface and at least partially extending into said first cylinder, and A locking mechanism for limiting their relative movement with respect to each other to prevent their separation on the first and second cylinders, And the first and second cylinders are slidably movable relative to each other. The method of claim 1, Said outer surface of at least one plate comprising a retaining ring, said inner surface of said plate being fitted within said retaining ring. The method of claim 1, And the core comprises a material selected from the group consisting of polymers, ceramics and metals. The method of claim 15, The metal is selected from the group consisting of cobalt chromium molybdenum, titanium and stainless steel. The method of claim 1, And the at least one elastic material is further disposed between the curved top and bottom surfaces of the core. The method of claim 17, And at least one elastic support member disposed in the elastic material and attached to the curved upper and lower surfaces. The method of claim 18, The at least one elastic support member includes a plurality of springs intervertebral disc prosthesis. The method of claim 1, Wherein said outer and inner surfaces of said plate comprise at least one metal selected from the group consisting of cobalt chromium molybdenum, titanium and stainless steel. The method of claim 1, The intervertebral disc prosthesis, wherein the core and the outer and inner surfaces comprise the same metal. The method of claim 1, Further comprising a restraining structure on at least one of the upper plate, the lower plate and the core to hold the core against at least one curved surface of the plate while the plate slides over the core. Intervertebral disc prosthesis characterized. The method of claim 22, And the restraint structure comprises a circumferential restraint structure. The method of claim 23, Intervertebral disc prosthesis, wherein the movement of the core in the confinement structure is free. The method of claim 1, The outer surface of the upper plate and the lower plate has at least one surface shape for promoting the attachment of the outer surface to the spine. The method of claim 25, The at least one surface form includes a plurality of teeth disposed along the outer surface. The method of claim 25, The at least one surface morphology includes an intervertebral disc prosthesis comprising a surface coated with plasma sprayed titanium. The method of claim 25, Said at least one surface form comprising a plurality of concavities formed by aluminum oxide blasting. The method of claim 25, Said at least one surface form comprising at least one fin disposed on each said outer surface. With the core, An intervertebral disc prosthesis comprising an upper plate and a lower plate disposed around the core, The core has a curved top and bottom surface and at least one elastic material disposed between the curved top and bottom surfaces, Wherein each plate has an outer surface engaging the vertebrae and a curved inner surface having a shape that can slide over one of the curved surfaces of the core. The method of claim 30, The at least one elastic material comprises an intervertebral disc prosthesis. The method of claim 30, The at least one elastic material intervertebral disc prosthesis, characterized in that it comprises a hydrogel. The method of claim 30, And at least one elastic support member disposed in the elastic material and attached to the curved upper and lower surfaces. The method of claim 33, wherein The at least one elastic support member includes a plurality of springs intervertebral disc prosthesis. The method of claim 30, Wherein the curved upper and lower surfaces of the core comprise a material selected from the group consisting of polymers, ceramics and metals. 36. The method of claim 35 wherein The metal is selected from the group consisting of cobalt chromium molybdenum, titanium and stainless steel. The method of claim 30, And the elastic material is further disposed between the outer surface and the inner surface of at least one of the upper and lower plates. The method of claim 37, wherein And the elastic material is disposed between the outer and inner surfaces of each plate. The method of claim 38, And at least one elastic support member disposed in said elastic material and attached to said outer and inner surfaces of each plate. The method of claim 39, The at least one elastic support member includes a plurality of springs intervertebral disc prosthesis. The method of claim 30, Wherein the outer and inner surfaces of the plate comprise at least one metal selected from the group consisting of cobalt chromium molybdenum, titanium and stainless steel. The method of claim 30, The intervertebral disc prosthesis of the core, the outer surface and the inner surface comprises the same metal. A method of making an endplate of an intervertebral disc prosthesis, Forming an outer surface of the end plate to be engaged with the spine, Forming a curved inner surface of the end plate to be slid over the curved surface of the core of the disc prosthesis, Connecting the outer and inner surfaces with at least one elastic support member disposed therebetween, and Disposing an elastic material between the outer surface and the inner surface to surround the elastic support member (s). The method of claim 43, Connecting the outer and inner surfaces with the elastic support member comprises attaching a plurality of springs between the two surfaces. The method of claim 43, Disposing an elastic material between the outer surface and the inner surface comprises injecting material between the surfaces. The method of claim 45, And said implanted material comprises a polymer. The method of claim 45, And said elastic material is injected into a cavity formed between the inner and outer end plates. The method of claim 45, Said elastic material is injected into a restraint structure disposed between said inner and outer end plates. The method of claim 43, Disposing an elastic material between the outer and inner surfaces comprises disposing one or more layers of solid material between the faces. The method of claim 43, Coupling at least one restraint structure to the outer and inner surfaces around the elastic material to retain the elastic material between the outer and inner surfaces. As a method of manufacturing an end plate of an intervertebral disc prosthesis, Forming an outer surface of the end plate to be engaged with the spine, Forming a curved inner surface of the end plate to be slid over the curved surface of the core of the disc prosthesis, Disposing an elastic material between the outer and inner surfaces, and Coupling said outer surface to said inner surface for confining said elastic material between said outer surface and said inner surface. As a method of manufacturing an end plate of an intervertebral disc prosthesis, Forming an outer surface of the end plate, the outer surface being engaged with the spine and having an retaining ring facing inwardly, Forming a curved inner surface of the end plate to be slid over the curved surface of the core of the disc prosthesis, Disposing an elastic material within the outer surface, Disposing the inner surface in the retaining ring of the outer surface to contain the elastic material between the two surfaces; and Shrinking at least a portion of the outer surface to maintain the inner surface in the glass ring. The method of claim 52, wherein Shrinking the outer surface includes the step of cooling the outer surface, The method further comprises heating the outer surface prior to placing the curved inner surface in the retaining ring. The method of claim 52, wherein And combining said outer and inner surfaces with at least one elastic support member. The method of claim 54, wherein And said elastic support member (s) comprise a spring. The method of claim 54, wherein And said elastic support member (s) comprise two cylinders, one of which is sized to be movable within the opposing piece.

Images